An analog delay line or digital feed forward equalizer (FFE) may be used alone or together with a decision feedback equalizer (DFE) in a communication system. The adaptation of the tap weights of the two equalizers is important. Although the optimal tap weights have well been studied in the literature, practical adaptation algorithms achieving desired performance with low implementation cost still invites innovations. For example, many text books assume the input signal to the FFE is available to the adaptation algorithm. While this is true if an analog-to-digital converter (ADC) is available, it is not the case for the analog delay line. In the case of an analog delay line, a new way of estimating the channel is needed.
In conventional approaches, the analog delay line or the FFE are used only to remove the precursor inter symbol interference (ISI), while the DFE is used to handle post cursor ISI. Optimal tap weights have been derived based on the above assumptions. In practical implementations, however, the analog delay line or FFE may be used to reduce post cursor ISI as well. The joint optimization between the analog delay line or FFE and the DFE becomes an interesting problem.
It would be desirable to implement a method and/or apparatus for implementing feed forward equalizer (FFE) tap weight adaptation based on channel estimation.